An HIV-positive used "sex, his own toxicity and deceit" in an attempt to infect unsuspecting young men he met online, the Crown attorney argued in court Thursday.

"Steven Boone was aroused by and deeply committed to achieving his goal of spreading HIV to his sexual partners," Crown attorney Louise Tansey-Miller told jurors.

The Crown can prove he succeeded once, she said.

The boyish-looking 30-year-old with gelled hair has pleaded not guilty to attempted murder and administering a noxious substance - HIV - to three men from January to April 2010. He is also charged with aggravated sexual assault against two of the men and three others.

"This case is not about pointing the finger at someone because of their sexual orientation or because they have a terrible and terminal disease," Tansey-Miller said. "This case is about Mr. Boone's intention to surreptitiously infect as many sexual partners as he could."

Jurors were introduced to the "disturbing" subculture of "bug-chasing," in which HIV-positive men seek out negative men to infect.

Some want to be infected but Boone engaged in "stealth pozzing" or trying to infect someone without their knowledge, Tansey-Miller said.

The evidence includes thousands of pages of MSN chats he engaged in after learning he had HIV in November 2009.

Boone admits he used MSN to set up sexual encounters, some of which actually occurred.

In some of the graphic chats, Boone is open about his HIV status and wanting to infect sex partners with his "strain."

He boasts he had sex with three virgins in a week and "knocked up all three," takes off the condom when a partner isn't looking and has "lost count" of the HIV-negative men he'd had unprotected sex with.

He says it's "hot" knowing that what he's doing "will change their lives forever" and that it's like being on Ecstasy.

Former roommate Matthew Baillie said Boone told him that it was hard to find a boyfriend when you're positive and "every time I tell them, they leave."

Baillie saw Boone's sex partners "coming and going" and one night he asked for lubricant. Baillie asked if he needed condoms.